Giving the fact that upgrading the jQuery version in an existing project is risky (see this my old post) i left the old declarations, but when i was verifying that all works as expected (inserting duplicated data) there was this error by clicking on every jQuery button after closing a jQuery dialog:

“Unable to get property ‘_focusTabbable’ of undefined or null reference”

This happened when my js code was simply displaying a message in a JQuery dialog: my work is to change the old , simple, plain “window.alert” with something better as user interface (remember that window.alert is really modal, the code is really stopped at the window.alert: with a modal jQuery dialog no!)

Effectively the Internet Explorer debugger shows the problem:

the object .data(“ui-dialog”) is null so the method ._focusTabbable() fails.

I found nothing of useful by googling, so i tried the very latest jQuery versions (at this moment, April 2013)